Immunohistochemical Expression of Calponin in Cutaneous Basal Cell Carcinoma

Calponin is an actin filament-associated protein significantly involved in the regulation of the cellular motility. Some data have indicated that overproduction of calponin in basal cell carcinoma (BCC) of the skin may be responsible for local tumor invasiveness and more aggressive biological behavior. We studied the immunohistochemical expression of calponin in a set of cutaneous BCCs, in order to clarify whether the presence of calponin in cancer cells may be a predictor of invasive tumor growth. The study group consisted of 37 primary BCCs categorized into a non-infiltrative subgroup (5 superficial, 16 nodular subtypes) and infiltrative subgroup (9 nodular-infiltrative, 7 infiltrative subtypes). A specific monoclonal antibody against calponin was used for staining. Expression of calponin in tumor tissue was found in 72.9% (27/37) of the cases, though staining intensity was relatively weak. In superficial, nodular, nodular-infiltrative, and infiltrative BCC subtypes, calponin positivity was found in 80% (4/5), 75% (12/16), 66.7% (6/9), and 71.5% (5/7), respectively. We did not confirm a significant correlation between expression of calponin and given, non-infiltrative, and infiltrative BCC subgroups. Furthermore, we found seven BCCs (18.9%) with striking immunoreactivity for calponin in adjacent peritumorous stroma. There was a significant association between stromal immunoreactivity for calponin and tumor growth histomorphology being positive only in BCCs with infiltrative growth features. Our study has shown that neoplastic cells in cutaneous BCC commonly produce calponin regardless of histological subtype. Expression of calponin in tumor tissue was not associated with the aggressive tumor phenotype. However, since some BCCs with infiltrative growth patterns strongly expressed calponin in peritumorous stroma, this finding could more reliably reflect the biological behavior of cancer and should be better explained in the future.